The elimination of 3:4-benzpyrene and other polycyclic hydrocarbons from the mouse.

IT has been shown that, after the intravenous injection of the carcinogenic hydrocarbons, 3:4-benzpyrene and methylcholanthrene, and of the non-carcinogenic hydrocarbon, anthracene, abnormally fluorescent bile is produced in rabbits, guinea-pigs, fowls and mice [Peacock, 1936]. So far, the fluorescent compounds present in such samples of bile have not been isolated, but spectrographic analysis appears to indicate the presence of derivatives of the injected aromatic hydrocarbons. The fluorescent substance, "BPX", found in the bile after the injection of 3:4-benzpyrene, has a characteristic fluorescence spectrum, and this property was utilized in the following attempt to trace the subsequent fate of this substance in the animal body. Objections to the use of fluorescence spectrum analysis as a means of following the fate of 3:4-benzpyrene in the animal organism have been raised by Sannie [1936] who obtained fluorescence curves of 0 5, 0 05 and 0-005 g. 3:4benzpyrene per 1. hexane, by examination of the fluorescence spectra with a microphotometer, and showed that "the fluorescence spectrum of benzpyrene varied markedly with concentration". He also indicated that the fluorescence spectrum of benzpyrene varied markedly with solvent, and quoted the finding of Winterstein et al. [1934], that the fluorescence of anthracene is extinguished by adding 1/30,000th part of naphthacene, and concluded that it was impossible to ascertain the fate of carcinogenic hydrocarbons in tissues solely from fluorescence data. Substances, such as naphthacene, may interfere with spectrum analysis made during the extraction of anthracene or 3:4-benzpyrene from coal tar, and similar experiments, but, presumably, such substances are not present in normal tissues. Auto-absorption or re-absorption of the fluorescence bands in strong solution may take place, as suggested by Sannie, but as Hieger [1937] has pointed out this property does not prevent quantitative fluorescence analysis being made by the method of comparison of the fluorescence of extracts with the fluorescence of standards photographed on the same plate. This method was first described by Berenblum & Kendal [1936] and has been used in this laboratory, Chalmers & Peacock [1936]. It should be noted that in these experiments each extract was made in a similar manner. Conclusions have not been drawn from small changes in the intensity of fluorescence but from changes readily seen even on visual examination of the fluorescent solutions.